A White House-appointed mediation panel Tuesday rejected an MTA proposal for a Long Island Rail Road union contract for the second time, calling labor leaders’ offer of a 17 percent, six-year pact a “reasonable” solution.

In its nonbinding recommendation issued last evening, the three-member Presidential Emergency Board 245 called the LIRR unions’ proposal for the contract and, for the first time, employee health benefit contributions “a reasonable balance addressing the priorities of both parties.”